1、GET _cluster/health

{
  "cluster_name" : "testcluster",
  "status" : "yellow",
  "timed_out" : false,
  "number_of_nodes" : 1,
  "number_of_data_nodes" : 1,
  "active_primary_shards" : 5,
  "active_shards" : 5,
  "relocating_shards" : 0,
  "initializing_shards" : 0,
  "unassigned_shards" : 5,
  "delayed_unassigned_shards": 0,
  "number_of_pending_tasks" : 0,
  "number_of_in_flight_fetch": 0,
  "task_max_waiting_in_queue_millis": 0,
  "active_shards_percent_as_number": 50.0
}

2、GET _cluster/stats?human&pretty

{
   "timestamp": 1459427693515,
   "cluster_name": "elasticsearch",
   "status": "green",
   "indices": {
      "count": 2,
      "shards": {
         "total": 10,
         "primaries": 10,
         "replication": 0,
         "index": {
            "shards": {
               "min": 5,
               "max": 5,
               "avg": 5
            },
            "primaries": {
               "min": 5,
               "max": 5,
               "avg": 5
            },
            "replication": {
               "min": 0,
               "max": 0,
               "avg": 0
            }
         }
      },
      "docs": {
         "count": 10,
         "deleted": 0
      },
      "store": {
         "size": "16.2kb",
         "size_in_bytes": 16684,
         "throttle_time": "0s",
         "throttle_time_in_millis": 0
      },
      "fielddata": {
         "memory_size": "0b",
         "memory_size_in_bytes": 0,
         "evictions": 0
      },
      "query_cache": {
         "memory_size": "0b",
         "memory_size_in_bytes": 0,
         "total_count": 0,
         "hit_count": 0,
         "miss_count": 0,
         "cache_size": 0,
         "cache_count": 0,
         "evictions": 0
      },
      "completion": {
         "size": "0b",
         "size_in_bytes": 0
      },
      "segments": {
         "count": 4,
         "memory": "8.6kb",
         "memory_in_bytes": 8898,
         "terms_memory": "6.3kb",
         "terms_memory_in_bytes": 6522,
         "stored_fields_memory": "1.2kb",
         "stored_fields_memory_in_bytes": 1248,
         "term_vectors_memory": "0b",
         "term_vectors_memory_in_bytes": 0,
         "norms_memory": "384b",
         "norms_memory_in_bytes": 384,
         "doc_values_memory": "744b",
         "doc_values_memory_in_bytes": 744,
         "index_writer_memory": "0b",
         "index_writer_memory_in_bytes": 0,
         "version_map_memory": "0b",
         "version_map_memory_in_bytes": 0,
         "fixed_bit_set": "0b",
         "fixed_bit_set_memory_in_bytes": 0,
         "file_sizes": {}
      },
      "percolator": {
         "num_queries": 0
      }
   },
   "nodes": {
      "count": {
         "total": 1,
         "data": 1,
         "coordinating_only": 0,
         "master": 1,
         "ingest": 1
      },
      "versions": [
         "5.5.1"
      ],
      "os": {
         "available_processors": 8,
         "allocated_processors": 8,
         "names": [
            {
               "name": "Mac OS X",
               "count": 1
            }
         ],
         "mem" : {
            "total" : "16gb",
            "total_in_bytes" : 17179869184,
            "free" : "78.1mb",
            "free_in_bytes" : 81960960,
            "used" : "15.9gb",
            "used_in_bytes" : 17097908224,
            "free_percent" : 0,
            "used_percent" : 100
         }
      },
      "process": {
         "cpu": {
            "percent": 9
         },
         "open_file_descriptors": {
            "min": 268,
            "max": 268,
            "avg": 268
         }
      },
      "jvm": {
         "max_uptime": "13.7s",
         "max_uptime_in_millis": 13737,
         "versions": [
            {
               "version": "1.8.0_74",
               "vm_name": "Java HotSpot(TM) 64-Bit Server VM",
               "vm_version": "25.74-b02",
               "vm_vendor": "Oracle Corporation",
               "count": 1
            }
         ],
         "mem": {
            "heap_used": "57.5mb",
            "heap_used_in_bytes": 60312664,
            "heap_max": "989.8mb",
            "heap_max_in_bytes": 1037959168
         },
         "threads": 90
      },
      "fs": {
         "total": "200.6gb",
         "total_in_bytes": 215429193728,
         "free": "32.6gb",
         "free_in_bytes": 35064553472,
         "available": "32.4gb",
         "available_in_bytes": 34802409472
      },
      "plugins": [
        {
          "name": "analysis-icu",
          "version": "5.5.1",
          "description": "The ICU Analysis plugin integrates Lucene ICU module into elasticsearch, adding ICU relates analysis components.",
          "classname": "org.elasticsearch.plugin.analysis.icu.AnalysisICUPlugin",
          "has_native_controller": false
        },
        {
          "name": "ingest-geoip",
          "version": "5.5.1",
          "description": "Ingest processor that uses looksup geo data based on ip adresses using the Maxmind geo database",
          "classname": "org.elasticsearch.ingest.geoip.IngestGeoIpPlugin",
          "has_native_controller": false
        },
        {
          "name": "ingest-user-agent",
          "version": "5.5.1",
          "description": "Ingest processor that extracts information from a user agent",
          "classname": "org.elasticsearch.ingest.useragent.IngestUserAgentPlugin",
          "has_native_controller": false
        }
      ]
   }
}

3、GET _cluster/pending_tasks

{
   "tasks": [
      {
         "insert_order": 101,
         "priority": "URGENT",
         "source": "create-index [foo_9], cause [api]",
         "time_in_queue_millis": 86,
         "time_in_queue": "86ms"
      },
      {
         "insert_order": 46,
         "priority": "HIGH",
         "source": "shard-started ([foo_2][1], node[tMTocMvQQgGCkj7QDHl3OA], [P], s[INITIALIZING]), reason [after recovery from shard_store]",
         "time_in_queue_millis": 842,
         "time_in_queue": "842ms"
      },
      {
         "insert_order": 45,
         "priority": "HIGH",
         "source": "shard-started ([foo_2][0], node[tMTocMvQQgGCkj7QDHl3OA], [P], s[INITIALIZING]), reason [after recovery from shard_store]",
         "time_in_queue_millis": 858,
         "time_in_queue": "858ms"
      }
  ]
}